From: Ian Campbell <Ian.Campbell@citrix.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: David Miller <davem@davemloft.net>,
"rientjes@google.com" <rientjes@google.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"hch@infradead.org" <hch@infradead.org>,
"jaxboe@fusionio.com" <jaxboe@fusionio.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH] mm: add a "struct page_frag" type containing a page, offset and length
Date: Fri, 14 Oct 2011 07:56:02 +0100 [thread overview]
Message-ID: <1318575363.11016.8.camel@dagon.hellion.org.uk> (raw)
In-Reply-To: <20111013142201.355f9afc.akpm@linux-foundation.org>
On Thu, 2011-10-13 at 22:22 +0100, Andrew Morton wrote:
> Looks OK to me. I'm surprised we don't already have such a thing.
>
> Review comments:
>
>
> > +struct page_frag {
> > + struct page *page;
> > +#if (BITS_PER_LONG > 32) || (PAGE_SIZE >= 65536)
>
> It does add risk that people will add compile warnings and bugs by
> failing to consider or test the other case.
>
> We could reduce that risk by doing
>
> #if (PAGE_SIZE >= 65536)
>
> but then the 32-bit version would hardly ever be tested at all.
Indeed. The first variant has the benefit that most 32-bit arches will
test one case and most 64-bit ones the other.
Perhaps the need to keep this struct small is not so acute as it is for
the skb_frag_t I nicked it from and just using __u32 unconditionally is
sufficient?
>
> > + __u32 page_offset;
>
> I suggest this be called simply "offset".
ACK.
Thanks,
Ian.
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next prev parent reply other threads:[~2011-10-14 6:56 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-13 10:02 [PATCH] mm: add a "struct page_frag" type containing a page, offset and length Ian Campbell
2011-10-13 20:33 ` David Rientjes
2011-10-13 20:37 ` David Miller
2011-10-13 20:49 ` David Rientjes
2011-10-13 20:51 ` David Miller
2011-10-13 21:22 ` Andrew Morton
2011-10-14 6:56 ` Ian Campbell [this message]
2011-10-18 8:49 ` Ian Campbell
2011-10-20 5:36 ` David Rientjes
2011-10-20 5:44 ` Andrew Morton
2011-10-20 8:59 ` David Miller
2011-10-20 9:04 ` Ian Campbell
2011-10-14 6:42 ` Jens Axboe
2011-10-14 9:17 ` David Rientjes
2011-10-14 9:54 ` Jens Axboe
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